First, Ballmer and company said that they would not sue open source developers for non-commercial development based on protocols that Microsoft has released. However, they also very specifically pointed out that they were not extending the same covenant to commercial developers. So, as News.com blogger and Alfresco Software VP Matt Asay puts it:

It's an imperfect commitment on Microsoft's part, almost undoubtedly driven by the need to placate European Commission regulators and to preemptively allay U.S. antitrust fears as a Yahoo deal nears.

He says open sourcers should "applaud even the baby steps" and then "push for more." His suggestion:

[O]ne thing that Microsoft could do is extend its Open Specification Promise to the API and protocol information it's opening up, rather than demanding license fees for these.